Re: Regression from 2.6.26: Hibernation (possibly suspend) broken on Toshiba R500 (bisected)

From: Rafael J. Wysocki
Date: Thu Dec 04 2008 - 17:47:00 EST

On Thursday, 4 of December 2008, Frans Pop wrote:
> On Thursday 04 December 2008, Linus Torvalds wrote:
> > On Thu, 4 Dec 2008, Frans Pop wrote:
> > > I've given your patch a try and the few resumes from STR I've done
> > > were all successful. That's not 100% conclusive yet, but a nice
> > > start. Some info from logs etc. below.
> >
> > Ok, but I thought you had a hard time reproducing this _anyway_, even
> > with just plain -rc7. No?
> Well, I had a failure rate of about 1 in 5-10 resumes originally.
> See:
> Then I found the 2 workarounds and *with those in place* I got almost 100%
> reliable resumes. Now I've removed those workarounds and with either the
> revert or your oneliner I still get 100% success.
> From my PoV that is a very definite improvement: the machine now "feels" a
> hell of a lot more reliable for critical use.
> So I _could_ reproduce it reliably given enough suspend/resume cycles.
> But I guess this does support your suspicion that it may be a timing
> issue: if the timing happens to be right, the resume succeeds; if it's
> wrong I get a dead box.
> > Since it's apparently STR, has anybody gotten _anything_ sane out of
> > trying to enable PM_TRACE_RTC, and then doing that
> >
> > echo 1 > /sys/power/pm_trace
> I did try that at the beginning. That's how I ended up removing e1000e
> before suspend. See
> My next hint was that Matthew Garret, who has the same notebook, was
> surprised at my resume problems as he did not see them. So I did a
> comparison of our kernel configs and made some changes to mine. From
> that I found that a very low value for SND_HDA_POWER_SAVE_DEFAULT (5)
> reduced the failure rate to practically zero.
> At some point I tried keeping e1000e loaded for a bit, but that quickly
> gave me a failure again, so I starting removing it again during suspend.
> So I did have some data, but as I got no response on my BR I had no idea
> where to go from there. I was really very happy to see Rafael's mail as
> his description almost exactly matched what I had been seeing.
> I'd be happy to run with unpatched kernels for a while and do some more
> pm_traces, but only if someone is going to follow up and interpret the
> results for me or provide suggestions for targeted additional debugging.

Please go for it, I'm very interested in understanding the underlying problem.

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